The LiaFSR system and antimicrobial peptide resistance in enterococci

LiaFSR 系统和肠球菌抗菌肽耐药性

• 批准号: 10553808
• 负责人: Cesar Augusto Arias
• 金额: $ 45.43万
• 依托单位: METHODIST HOSPITAL RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-02-01 至 2023-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10553808
• 关键词: LiaFSR; system; antimicrobial; peptide; resistance

ABSTRACT The emergence of antibiotic-resistant bacteria is one of the greatest threats to human health in the 21st century. In particular, vancomycin-resistant enterococci (VRE) are one of the most challenging organisms in clinical settings. Indeed, vancomycin-resistant Enterococcus faecium have been designated by the Infectious Disease Society of America as one of the “superbugs” against which new therapies are urgently needed. Daptomycin (DAP), a cell membrane-targeting lipopeptide antibiotic with potent in vitro bactericidal activity against VRE, has become a key “front-line” antimicrobial agent against these organisms. However, development of resistance during therapy is a daunting challenge. The major mediator of DAP resistance in enterococci is a cluster of genes (designated liaFSR) that encode a three-component regulatory system involved in orchestrating the cell envelope adaptive response to antibiotics and antimicrobial peptides. LiaR is the response regulator (LuxR-type) of the system whose activity seems to be regulated by LiaF and LiaS (histidine kinase). However, the specific regulatory role of LiaF in enterococci is unknown. Additionally, we have identified a cluster of three genes that are mediators of the LiaR response (designated liaXYZ). LiaX is a surface exposed and secreted protein that appears to be the main orchestrator of the LiaR- mediated cell membrane response by negatively regulating the LiaFSR system, controlling cell membrane phospholipid remodeling (a phenotype associated with DAP resistance). Additionally, the N-terminus of LiaX interacts with penicillin-binding protein 5 (a key enterococcal enzyme required for cell-wall synthesis in the presence of β-lactams) and is likely to mediate the “see-saw” effect (hypersusceptibility to β-lactams upon developing of DAP resistance). LiaY and LiaZ are two transmembrane proteins that are regulated by LiaX. Our data indicate that LiaYZ are required for DAP resistance and that LiaY is likely responsible for changes in cell membrane phospholipid architecture. Thus, the overarching hypothesis of our proposal is that understanding the mechanisms by which LiaFSR and LiaXYZ orchestrate the cell membrane response against antibiotics would provide novel insights into the molecular mechanisms of antimicrobial peptide resistance and bacterial adaptation that could be exploited with novel therapeutic interventions. We plan to develop our experimental approach in three major specific aims. In Sp. Aim I, we will investigate of the role of LiaF, a transmembrane protein that seems to play a major and distinct role in the activation of the response regulator LiaR in enterococci. In Specific Aim II, we will focus on the characterization of LiaX as the master effector of the cell envelope adaptive response. Specific Aim III will assess the role LiaYZ as mediators of DAP resistance and cell membrane remodeling under the assumption that such effect is mediated through interactions with cardiolipin synthase, a major phospholipid enzyme. We expect to provide evidence for a novel biochemical paradigm to the cell envelope response to antibiotics and, potentially, new targets for drug development.

抽象的 耐药细菌的出现是21世纪人类健康面临的最大威胁之一 特别是，耐万古霉素肠球菌（VRE）是当今最具挑战性的微生物之一。 事实上，耐万古霉素屎肠球菌已被传染病部门指定。 美国疾病协会将其视为“超级细菌”之一，迫切需要新的治疗方法。 达托霉素（DAP），一种具有有效体外杀菌活性的细胞膜靶向脂肽抗生素 抗 VRE，已成为对抗这些生物体的关键“前线”抗菌剂。 治疗过程中耐药性的产生是一项艰巨的挑战，这是 DAP 耐药性的主要介质。 肠球菌是一组基因（称为 liaFSR），编码三部分调节系统 参与协调细胞对抗生素和抗菌肽的适应性包膜反应。 LiaR 是系统的反应调节器（LuxR 型），其活动似乎受 LiaF 调节 LiaS（组氨酸激酶） 然而，LiaF 在肠球菌中的具体调节作用尚不清楚。 此外，我们还鉴定了一组三个基因，它们是 LiaR 反应的调节者（指定为 LiaX 是一种表面暴露和分泌的蛋白质，似乎是 LiaR-的主要协调者。 通过负调节 LiaFSR 系统介导细胞膜反应，控制细胞膜 磷脂重塑（与 DAP 抗性相关的表型）此外，LiaX 的 N 末端。 与青霉素结合蛋白 5（细胞壁合成所需的关键肠球菌酶）相互作用 β-内酰胺的存在），并可能介导“拉锯”效应（对 β-内酰胺过度敏感） LiaY 和 LiaZ 是受 LiaX 调节的两种跨膜蛋白。 我们的数据表明，LiaYZ 是抵抗 DAP 所必需的，并且 LiaY 可能是造成变化的原因 因此，我们提议的总体假设是： 了解 LiaFSR 和 LiaXYZ 协调细胞膜反应的机制 抗生素将为抗菌肽耐药性的分子机制提供新的见解 我们计划开发我们的细菌适应新的治疗干预措施。 在 Sp.Aim I 中，我们将研究 LiaF 的作用。 跨膜蛋白似乎在反应调节剂的激活中发挥着重要而独特的作用 肠球菌中的 LiaR。在 Specific Aim II 中，我们将重点关注作为肠球菌主要效应子的 LiaX 的表征。 细胞包膜适应性反应将评估 LiaYZ 作为 DAP 抗性介质的作用。 和细胞膜重塑，假设这种效应是通过与 心磷脂合酶，一种主要的磷脂酶，我们希望为新型生化酶提供证据。 细胞膜对抗生素反应的范例，并可能成为药物开发的新目标。